Frequently Asked Questions

DigiSim.io is a professional web-based platform for learning, designing, and simulating digital logic circuits. It provides an interactive environment with a comprehensive library of components, from basic logic gates to complex CPU architectures, designed for students, educators, and professionals.

No! DigiSim.io runs entirely in your web browser. Simply visit our website and start designing circuits immediately. We recommend using a modern browser like Chrome, Firefox, Safari, or Edge for the best experience.

Yes! We offer a free tier that includes access to the core simulator, basic & derived logic gates, I/O components, and essential tools. Circuits save locally in your browser (IndexedDB) at no cost, and you can download .digi files at any time. For more advanced components and SimCast lessons, consider the DigiSim Pro — a one-time purchase with no recurring fees.

Getting started is easy: Navigate to the Playground from the main menu, drag components from the component palette on the left to the workspace, connect components by clicking on output pins and dragging to input pins, use input switches and clocks to control your circuit, and watch output lights and displays show real-time results.

DigiSim.io works on any device with a modern web browser. It runs best on desktops and laptops (Windows, macOS, Linux, ChromeOS) where you have a mouse or trackpad for precise component placement and wiring. Tablets can be used for viewing and running simulations, but the design experience is optimized for larger screens with pointer input.

You can explore the Playground and build circuits without creating an account. Circuits are saved locally in your browser regardless of login state. An account is required to access SimCast lessons, template circuits, and to manage purchases. Logging in on a different browser or device does not transfer your locally saved circuits — export them as .digi files to move work between devices.

Yes! DigiSim includes a template circuits library with pre-built designs covering common topics like adders, counters, ALUs, and more. Templates are a great way to learn — you can open one, study how it works, modify it, and save your own version. Access templates from the File menu or the Templates section in the Playground.

DigiSim.io includes a comprehensive library: Basic Logic Gates (AND, OR, NOT, NAND, NOR, XOR, XNOR, Buffer), Input/Output (Switches, Constants, Output Lights, Seven-Segment Displays), Combinational Logic (Multiplexers, Demultiplexers, Encoders, Decoders), Arithmetic (Half/Full Adders, 4-bit and 8-bit Adders, ALUs, Comparators), Sequential Logic (Flip-Flops, Latches, Registers, Counters), Memory (RAM 256×8, ROM 256×8), CPU Components (Program Counter, Instruction Register, Control Unit), and Advanced (Assembly Program Loader, Oscilloscope, Pixel Screen).

Our platform includes both 4-bit and 8-bit versions of many components. 4-bit components are ideal for learning fundamental concepts and building smaller circuits, while 8-bit components are better for more realistic computer architecture projects and advanced simulations. Note that full CPU components and advanced 8-bit systems are available with the DigiSim Pro.

DigiSim.io uses an advanced event-driven simulation engine that accurately models signal propagation delays and timing behavior. This means you can observe realistic timing relationships, analyze sequential circuits, and understand how real digital systems operate.

The Assembly Program Loader allows you to write assembly code and automatically load it into RAM components. This is perfect for CPU projects where you want to test your processor design with actual programs. It supports a custom assembly language with standard instructions like LDA, STA, ADD, and JMP. This feature is available with the DigiSim Pro, which includes the full CPU component library.

DigiSim currently provides a curated library of professionally designed components. While you cannot create entirely new component types from scratch, you can combine existing components into subcircuits that act as reusable building blocks in larger designs. This lets you encapsulate common patterns — like an ALU or a register file — and reuse them without rebuilding each time.

The Seven-Segment Display is an output component that visually renders hexadecimal digits (0-F) just like the numeric displays found on real-world electronics such as clocks, calculators, and instrument panels. It accepts a multi-bit input and lights up the appropriate segments. It is great for visualizing counter outputs, ALU results, or memory contents in a human-readable way.

The Pixel Screen is an advanced output component that lets you drive a small grid of pixels from your circuit, enabling simple graphics output. It is commonly used in CPU projects to demonstrate video output or to create visual feedback beyond simple LEDs and seven-segment displays. The Pixel Screen is available with the DigiSim Pro.

Connecting components is intuitive: Click on an output pin (right side of components), drag to an input pin (left side of components), release to create the connection. Connected pins show their logic state with color coding (high/low/high-impedance).

Make sure you've properly connected all pins and that your input sources (switches, clocks) are set correctly. For sequential circuits, ensure clock signals are connected and that you understand the timing requirements. Use the debugging tools like the oscilloscope to analyze signal timing.

The clock component generates periodic signals essential for sequential circuits. Right-click on the clock to adjust its frequency. Connect the clock output to components that need timing signals, such as flip-flops, registers, and counters.

The Oscilloscope displays voltage waveforms over time and is perfect for analyzing timing relationships, debugging sequential circuits, understanding propagation delays, and verifying clock synchronization. The free tier includes basic timing analysis, while the DigiSim Pro provides an advanced 8-channel oscilloscope for complex analysis.

Building a CPU is one of our most advanced projects and requires the DigiSim Pro for access to the full CPU component library. Start with our demo circuits: Begin with the Program Counter and Clock, add ROM/RAM for instruction and data storage, include the Instruction Register and Control Unit, connect the ALU and processor registers, wire the address and data buses, and use the Assembly Program Loader to test with actual programs.

Start by checking the basics: verify every pin is connected (unconnected inputs float and cause unpredictable behavior), confirm your input switches are in the expected state, and look at the wire colors to trace signal values through the circuit. For sequential circuits, attach the Oscilloscope to key signals to inspect timing. You can also simplify by disconnecting sections of the circuit and testing them in isolation to locate the problem.

Yes. DigiSim's event-driven simulation engine models propagation delays so you can observe how signals ripple through your circuit over time. This is essential for understanding race conditions, setup/hold time violations, and why certain sequential designs require specific clocking strategies. Use the Oscilloscope to visualize these delays on a time axis.

Yes. DigiSim supports undo and redo in the Playground so you can freely experiment without fear of breaking your circuit. Use the standard keyboard shortcuts (Ctrl+Z to undo, Ctrl+Shift+Z or Ctrl+Y to redo) or the buttons in the toolbar to step back and forth through your recent actions.

DigiSim saves circuits locally in your browser using IndexedDB — no account or internet connection needed once the app is loaded. To back up your work or move it to another device, use File → Export to download your circuit as a .digi file. You can store .digi files anywhere you like (your hard drive, Google Drive, Dropbox, etc.) and reload them via File → Import.

There is no quota on locally saved circuits. Your browser's IndexedDB storage is the only practical limit, which is many gigabytes on modern devices. You can also export unlimited .digi files to disk — there are no restrictions.

DigiSim.io uses its own .digi file format optimized for our simulation engine. While we don't directly import from third-party formats, you can recreate circuits quickly using our intuitive drag-and-drop interface and save them locally.

Yes — export your circuit as a .digi file (File → Export) and send it via email, your LMS, or any file-sharing service. Recipients import the file into their own DigiSim Playground using File → Import. This is the recommended way for professors to distribute starter circuits and for study groups to collaborate.

No. DigiSim does not offer public share links, live circuit-sharing URLs, or real-time collaboration. To distribute a circuit, export it as a .digi file and share that file directly via email, your LMS, or any file-sharing service.

Circuits saved in your browser are specific to that browser and device. They do not sync automatically to other browsers or devices. To move your work, export your circuits as .digi files before switching devices and import them wherever you need them.

SimCast is DigiSim's interactive lesson format — guided tutorials that show step-by-step how to build and understand digital circuits. Each SimCast includes narrated instructions, automatic component placement and connection, educational explanations of circuit principles, and progressive complexity from basic gates to complete systems. The free tier includes access to a selection of introductory SimCast lessons, while the DigiSim Pro provides access to the complete SimCast library.

Absolutely! DigiSim.io is designed with education in mind: No software installation required, structured learning progression from basic to advanced concepts, built-in documentation for every component, and demo circuits demonstrating key concepts.

Our platform serves multiple educational levels: High School (basic logic gates and simple circuits), Undergraduate (sequential logic, computer architecture, processor design), Graduate (advanced timing analysis, complex system design), and Professional (prototyping and educational demonstration).

DigiSim is primarily a self-directed design and simulation tool rather than a full LMS. However, professors can distribute starter circuits via .digi files, have students submit their completed designs for review, and use the template library to set up consistent assignments. Students can export their work at any time, making it easy to submit through your institution's existing grading platform.

DigiSim does not include a built-in grading engine, but it pairs well with your existing course workflow. Professors commonly create a starter circuit, distribute it to students, and then collect the completed .digi files for manual or automated evaluation. Because circuits are saved as JSON-based files, tech-savvy instructors can write scripts to verify expected outputs programmatically.

SimCast lessons follow a structured curriculum that mirrors a typical digital logic course. Early lessons cover basic gates and truth tables, then progress through combinational logic, arithmetic circuits, latches and flip-flops, registers and counters, memory systems, and ultimately full CPU design. Each lesson builds on concepts from previous ones, so working through them in order is recommended.

DigiSim uses a one-time purchase model with four tiers: Free, Fundamental, Professional, and Max. You pay once and get access. No subscriptions, no recurring charges.

You will NEVER lose your projects. On the Free tier you can still log in, view your circuits, run simulations, and export your files. You have limited access to paid components and SimCast lessons. Your data remains safe and accessible.

Yes. You can upgrade at any time and you only pay the difference in price between your current tier and the higher one.

We have a strict "No Data Lock-in" policy. You can download your source files (JSON) at any time. Even if our servers go offline, you possess the raw data of your designs. We guarantee a minimum 30-day notice period with full export access before any shutdown.

Absolutely! DigiSim is widely used in university courses. Even on the Free tier, you can still show your designs to future employers or professors. Upgrading unlocks more components and lessons for your coursework.

Yes. Students, educators, and researchers with an academic email (.edu, .ac.uk, etc.) receive a significant discount automatically at checkout. No coupon code needed.

We accept payments through Stripe, which supports major credit cards, debit cards, and various local payment methods. All transactions are secure and encrypted.

One-time purchases are generally non-refundable, except as required by law. We encourage you to fully explore the Free tier before purchasing to ensure DigiSim meets your needs.

The Free tier is available to all users at no cost. You can build circuits, run simulations, save locally in your browser, and export .digi files — all without paying. You have access to basic logic gates and a selection of introductory SimCast lessons.

Free gives you basic logic gates and a selection of introductory lessons. Fundamental adds NAND, NOR, XOR, and XNOR gates plus more lessons. Professional adds arithmetic, routing, and sequential components. Max adds registers, memory, CPU architecture, and the full SimCast library.

No. Each license is tied to a single user account and is not transferable. However, students, educators, and researchers can apply the academic discount at checkout with an academic email.

DigiSim.io works best on modern browsers: Recommended: Chrome 90+, Firefox 88+, Safari 14+, Edge 90+. Required: JavaScript enabled, minimum 1GB RAM. Optimal: 1920×1080 resolution or higher for the best workspace experience.

For optimal performance: Use a modern browser with hardware acceleration enabled, close unnecessary browser tabs and applications, for large circuits consider breaking them into smaller subcircuits, and disable browser extensions that might interfere with canvas rendering.

We value your feedback! You can email us directly at support@digisim.io, use the feedback button in the application, include steps to reproduce any issues, and attach relevant circuit files if applicable.

Yes. All data transmission is encrypted using HTTPS. Circuits you create are stored locally in your browser's IndexedDB — they never leave your device unless you explicitly export or import a .digi file. We never share your personal information with third parties, and you maintain full ownership of your circuit designs.

No problem! Use the "Forgot Password" link on the login page to reset your password. You'll receive an email with instructions to create a new password and regain access to your account and saved circuits.

DigiSim requires an internet connection to initially load the application and authenticate your account. Once the Playground is loaded, basic circuit design and simulation continue to work if your connection drops temporarily — circuits save to your browser's local storage regardless. SimCast lessons and template circuits require connectivity to load. For a portable backup, export your circuits as .digi files which can be stored anywhere.

DigiSim is optimized for desktop and laptop browsers where you have a mouse or trackpad for precise wiring and component placement. While the application will load on tablets, the design experience is best on screens 1024px or wider. Mobile phones are not recommended for circuit design due to the small screen size, though you can view and run previously built circuits on any device.

DigiSim supports standard shortcuts to speed up your workflow: Ctrl+Z / Cmd+Z to undo, Ctrl+Shift+Z / Cmd+Shift+Z to redo, Ctrl+S / Cmd+S to save, Ctrl+C / Cmd+C and Ctrl+V / Cmd+V to copy and paste components, Delete or Backspace to remove selected components, and scroll wheel to zoom in and out on the workspace.